Investments (Unconsolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Carrying Amount Asset	$ 73,034	$ 71,339
Carrying Amount Liability	79,304	77,008
Other limited partnership interests
Variable Interest Entity [Line Items]
Carrying Amount Asset	6,344	6,208
Carrying Amount Liability	12,136	11,282
Other invested assets
Variable Interest Entity [Line Items]
Carrying Amount Asset	2,302	2,261
Carrying Amount Liability	2,762	2,837
Other
Variable Interest Entity [Line Items]
Carrying Amount Asset	382	252
Carrying Amount Liability	400	271
Structured securities (RMBS, CMBS, and ABS)
Variable Interest Entity [Line Items]
Carrying Amount Asset	61,218	59,773
Carrying Amount Liability	61,218	59,773
U.S. corporate and foreign corporate securities
Variable Interest Entity [Line Items]
Carrying Amount Asset	2,788	2,845
Carrying Amount Liability	$ 2,788	$ 2,845